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    copied!<p>Fixed it!</p> <p>This is very similar to @DRobinson's solution, but using a proc and a has_many definition instead of defining a local method.</p> <p>According to the 3.1 release notes you can now use a proc in a condition!</p> <p>Inside the proc, self is the object which is the owner of the association, unless you are eager loading the association, in which case self is the class which the association is within.</p> <pre><code>class User &lt; ActiveRecord::Base has_many :incomplete_transactions , :class_name =&gt; 'Transaction', :conditions =&gt; proc { incomplete_sales + incomplete_purchases } has_many :incomplete_sales, :class_name =&gt; 'Transaction', :foreign_key =&gt; 'seller_id', :conditions =&gt; { :buyer_id =&gt; nil } has_many :incomplete_purchases, :class_name =&gt; 'Transaction', :foreign_key =&gt; 'buyer_id', :conditions =&gt; { :seller_id =&gt; nil } has_many :selling_transactions, :class_name =&gt; 'Transaction', :foreign_key =&gt; 'seller_id' has_many :buying_transactions, :class_name =&gt; 'Transaction', :foreign_key =&gt; 'buyer_id' end class Transaction &lt; ActiveRecord::Base belongs_to :seller, :class_name =&gt; 'User' belongs_to :buyer, :class_name =&gt; 'User' # scope :incomplete_sales , :conditions =&gt; {:buyer_id =&gt; nil} # scope :incomplete_purchases , :conditions =&gt; {:seller_id =&gt; nil} end </code></pre> <p>See: </p> <ul> <li><a href="http://guides.rubyonrails.org/3_1_release_notes.html" rel="nofollow">http://guides.rubyonrails.org/3_1_release_notes.html</a></li> </ul>
 

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